This is a resubmission of an Extramural/Intramural Alcohol Research Collaboration (U01) Application entitled Oxidized Metabolites of Linoleic Acid in Alcohol-induced Liver Injury. Alcoholic liver disease (ALD) remains a major cause of chronic illness and death. Despite extensive investigation into ALD pathogenesis, the specific mechanisms responsible for development and progression are incompletely understood. Increased oxidative stress is a core abnormality responsible for liver injury in ALD. Based on our extensive preliminary findings we propose the CENTRAL HYPOTHESIS that oxidized linoleic acid (LA) metabolites (OXLAMs) generated via the 12/15-LO mediated pathway play a critical role in the development and progression of alcohol-mediated hepatic and intestinal injury. We have established a collaborative team with extensive expertise and unique resources that will allow us to accomplish our goals by using in vivo experimental animal models of ALD, in vitro cell culture models, and collaborating with the unique human populations of an ongoing NIAAA Clinical Center randomized trial on dietary linoleic acid (LA) reduction and an NIAAA sponsored U01 clinical trial on alcoholic hepatitis (AH). State-of-the-art technologies including Lipidomics (LC/ESI/MS/MS), Seahorse (to investigate mitochondria dysfunction), Cellomics (the high-throughput technique for cell image-acquisition and analysis) will be utilized in this proposal. FIRST, we will test the hypothesis that OXLAMs are specific mediators of liver damage and intestinal barrier disruption in ALD. We will establish the role of dietary LA and OXLAMs in the induction of hepatic steatosis/injury and intestinal hyper-permeability in murine models of ALD. SECOND, we will evaluate in in vitro systems potential mechanisms by which OXLAMs enhance ethanol-mediated liver damage and disruption of intestinal barrier integrity. We will determine the effect of OXLAMs and their interactions with alcohol on mitochondrial function in hepatocytes and integrity of tight junctions in intestinal epithelium. THIRD, we will evaluate the ability of controlled dietary lowering of LA in humans to reduce circulating OXLAMs, endotoxin/gut permeability, and liver steatosis/injury (NIAAA intramural RCT). We will test the hypothesis that, compared to a control diet containing 8 % of energy as LA, lowering LA to 1% of energy for 12 weeks will result in significant reductions in: liver steatosis assessed by 3T-MRI; OXLAM and LA content of plasma, circulating endotoxin, and serum CK-18 (total and fragmented) levels (two robust markers of hepatocyte injury). FINALLY, we will establish levels of OXLAMs in human Alcoholic Hepatitis and their relation to disease severity and mortality (NIAAA U01 program). This study will help to elucidate a novel biochemical pathway involved in the pathogenesis of ALD. The findings could provide novel targets for biomarkers and drug development, and could identify a potential nutritional strategy for ameliorating liver disease.